This invention relates to diagnostic NMR imaging.
NMR imaging has been used in medical diagnosis for a number of years. It is known that certain paramagnetic substances, e.g., ionic manganese, can reduce the spin lattice relaxation time (T1) of surrounding water protons in vitro, and manganese has been used in in vivo experiments to provide NMR contrast between healthy and infarcted myocardial tissue.
Lauterbur (1978) Frontiers of Biological Energetics 1, 752 describes the use of ionic manganese to provide such contrast in dogs in which myocardial infarctions were induced prior to manganese administration and NMR imaging: "The ischemic region of the heart is clearly delineated by the relaxation rates and by the manganese concentrations."
Brady et al. (1982) Radiology 144, 343 discussed Lauterbur, supra: "using in vitro NMR spectroscopic analysis of tissue, Lauterbur et al. demonstrated that the manganese distribution to normal myocardium allowed differentiation between normal and ischemic or infarcted tissue, due to enhanced proton relaxation time." Brady et al. go on to report similar experimental results: "(T)hose (hearts) with manganese demonstrated a clearly demarcated zone of reduced signal intensity consistent with the ischemic zone."